There has been known an image forming apparatus of an electrophotographic type including a cleaning unit which collects developer attached on an endless belt which contacts a plurality of photosensitive drums (for example, refer to JP-A-2010-101990).
Specifically, the photosensitive drums are supplied with developer from a plurality of developing cartridges which are provided for the plurality of photosensitive drums, respectively. The photosensitive drums are held by a drum holding member which can be drawn relative to an apparatus main body. Also, the developing cartridges are held by a developing cartridge holding member which can be drawn relative to the apparatus main body.
The cleaning unit has a collecting member which contacts the endless belt to thus collect the developer attached on the endless belt, and an accommodating part which accommodates the developer collected by the collecting member. The collecting member is held to the drum holding member, and the accommodating part is held to the developing cartridge holding member, which facilitate replacement of the cleaning unit.